Recently, as electronic products are being made in a small size, smart watches that can be worn at a place with good accessibility such as wrists or ends of shirt sleeves are being released.
Such smart watches have an advantage of providing mobility and convenience. However, in smart watches, a display area is small and a volume of the main body is so low that checking time, simple calls, or other data communication is possible, and there is a problem in that functions and capacity are considerably limited.
Meanwhile, a device required for a smart watch may include various electronic circuit elements. The electronic circuit elements may be integrated into a semiconductor substrate called a semiconductor chip or die. A semiconductor chip package is employed in electronic products such as computers, mobile devices, or data storages.
However, as the demand for mobility of an electronic product such as a smart watch increases, interest in a stacked package structure that can be bent or curved is increasing.
As interest in wearable electronics that can be worn on the face in the form of glasses or on the wrist in the form of a watch or bracelet requiring mobility has increased, flexibility characteristics such as bending or curving is required in the electronic products.